I think my head is gone

Driving along the motorwaqy when all of a sudden the disco overheated. I pulled over allow her to cool refilled the system only for the samething to happen again. I have no heat in the car. No water in the oil nor oil in the water.

I thought maybe the thermosat so i took it out still same no heat in the car and overheating after 30 miles.

The waterpump started to squeel so i have replaced it. I noticed that the rad wasn't too clean so i cleaned that back flushed the whole system. Took it for a 10 mile drive today all fine.

Going to try the motorway tomorrow but i have a feeling that the head is gone, or on it way.

What do everyone else think. What the best way of checking.

turborange said:

Driving along the motorwaqy when all of a sudden the disco overheated. I pulled over allow her to cool refilled the system only for the samething to happen again. I have no heat in the car. No water in the oil nor oil in the water.

I thought maybe the thermosat so i took it out still same no heat in the car and overheating after 30 miles.

Click to expand...

all of that suggests shagged pump.Might have saved the head by replacing it in time.If the head is shgged there could be more to do then just that if its cooked

today the wife drove it round stop starting it no problems but still no heat from the heater. I have finished work taken the pipes off from the heater with the engine running and nothing. No water at all coming through. If i apply pressure to the system then the water flows. If i connect the hose back on the heater and apply pressure to the system water flow throught the matrix.

This tells me that there is no internal blockage.

When i pressurise the system i am doing so by blowing in the expansion bottle.

I don't want to do the head unless i know for sure then i will rip it off, but i only want to do it if it is needed.

well what can i say. i got 10 miles down the motorway and the disco overheated!!!
Removed the thermosat and ran it with no thermosat still overheated. Bottom hose isn't getting hot. Heater not getting hot

I had two 300TDi that both did ***exactly*** this.

I replaced the water pump, P Gasket behind the pump, and the thermostat. P Gasket is pain in the backside, and had me fooled into thinking the head had gone, and only after close inspection (water pump off) did I find that it was leaking.

A pain the butt, but replace the three. If it still overheats...suspect the head gasket.

There's a good webpage about replacing the P Gasket, take a look at that before doing anything else.

If it hasn't overheated, then I would put a bet on the P Gasket.

Well worth doing anyway, as you don't want the 'ngine going pop !

Ta

Also check the rear (engine bay side) of the radiator for missing fins. Mine did this and after we took the radiator out we could see almost all the rear fins were blown out. A new radiator cured it. You couldn't see the missing fins without removing the fan shroud, or as we did by removing the rad ... don't forget the oil cooler is integral to the rad, and we suspect it was the oil not cooling that really didn't help the engine temperature!

You could also have an air lock, or low coolant level , I do not understand why you have no circulation through the heater pipes this is very significant ?? Your initial description sounds like a failed water pump . If you run a 300tdi without a thermostat it could still over heat because the thermostat is designed to open and allow flow out of the top pipe into the top of the radiator and importantly at the same time close the radiator bypass pipe . This is the short rubber pipe conecting the back of the thermosat housing to the top of the water pump . A leak from a place like the P gasket will also give symptoms you describe . Get a garage to do a pressure test on your cooling system and to check the cooling system for combustion gasses , these two tests will confirm a leaky system and / or a head gasket problem . The cheapest fix you can doin the short term is to put a new thermostat in and as the system is supposed to be pressurised to 15 psi possibly a new cap on the expansion tank , but you need to confirm that there are no leaks ASAP . Genuine thermostats are made by Waxstat . Coolant level is very important on a 300Tdi and a leaky system can soon cause a problem . Regards Jonathan

to echo the above, dont assume that the head has gone, the 300tdi is a bugger to refil without airlocks, I do it by raising the front end up on stands or ramps, than use a hose pipe in the hose from the thermostat top to the heater .

I have bought a sniff tester and have tested the coolant for gases with this today. I tried the expansion tank, radiator and the thermostat housing and turned up negative.

I can't see any leaks from the P gasket or any other pipes. The rad is flowing and all fins are complete.

There is pressure building up in the expansion tank though.

Will now order a new stat.

Today i have bought and fitted a new thermosat. Still overheating!!!!!! Done another sniff test still negative.

Heater still cold as are the pipes at the back of the engine.

Took it for a drive until it got hot and the expansion bottle was cold but under pressure. I released this which was followed by a small gush of water.

ANYONE WITH ADVICE?????????????????????????????

If its hot - of course the expansion bottle will be under pressure. sounds like an air lock - or a blocked heater matrix.
try reverse flushing the heater matrix.

have you checked the main radiator for cold spots? get yoself an infra red thermometer.

i will try flushing the matrix again tomorrow. I did disconnect the small pipe that gone to the heater to bottom hose to check for flow. nothing was coming from the metal pipe. I then removed the expansion cap and blew in to the bottle (creating pressure) then water came out of the metal pipe. This would indicate to me that water is able to flow.

what you could try is attaching your hosepipe to the heater feed pipe and pressure flushing the whole system, keeping trying cos the 300tdi is a pig to clear all the airlocks from. as I said in my previous post try elevating the front end while flushing this sometimes helps

Re the cold heater my first instinct would aslo be an air lock. Have you checked the pressure cap?

Heater still cold as are the pipes at the back of the engine. This makes me think , AIR LOCK ,or BLOCKAGE or WATER PUMP FAILURE . The heater pipes should get hot first before the radiator. Regards Jonathan

Well decide to bite the bullet abd take the head off and get it head. And there now lies my problem. I have a cracked head but the crack only opens under full pressure.

Thanks for all your help,

Now time to find a head